The present invention relates to an image display device and, more particularly, to an image display device adapted to display image data of page units in regular sequence, which is capable of succesively displaying image data of a next page at a display position and in a display state at and in which image data of the previous page were displayed when image data of plural pages are displayed in consecutive order. The present invention is further directed to an image display method applicable to the image display device.
The image display device is preferred for displaying image data when an image size is to be displayed on each page for image data of a page unit or an enlarged size of an image is to be displayed larger than a displayable size on a display screen of the display unit.
Generally, image data are displayed by means of the display method which displays input image data as it is. This display method, however, can display only a portion of input image data if image data that is larger than a displayable size on the display screen of the display unit are to be entered. In this case, accordingly, an undisplayed portion of the image data should be displayed by scrolling a displayed image on the display screen thereof in longitudinal and/or transverse directions by means of an operation of a scrolling key.
The method of using the scrolling key of the display device, however, suffers from the disadvantage that the scrolling operation which displays each portion of the image data on the display screen is rendered more laborious as the image size of the input image data becomes larger, thus leading to a poor operability.
In order to improve such a poor operability with the method using the scrolling key, Japanese Patent Publication (laid-open) No. 19,893/1987 discloses an image scrolling method which is designed such that a rectangular portion of an original image to be displayed is computed on the basis of a display position assignment from the operator, the rectangular portion thereof is scrolled, and the image after scrolling is displayed. This scrolling method permits a display position assignment by means of a one-touch operation of keys from key 1 to key 9 of a numeric key pad, whose positions correspond, respectively, to the display position assignments on the display screen from the operation unit, thus improving the operation.
In displaying image data exceeding a size capable of being displayed within a displayable size of a display screen or in displaying an objective image display site of image data in an objective display state, the display of such image data is usually such that the original image is displayed as the image data stand and that the objective display site of the image data is then displayed in the objective display state in accordance with an instruction by an operator's instruction for altering a display state of the image by means of an operation for enlargement, reduction, rotation or scrolling.
Sequentially continous display of plural pages of image data can be effected by repeating the above operation for the image data of each page. More specifically, image data of a certain page is first displayed at an objective display position and in an objective display state on the display screen by means of operation for enlargement, reduction, rotation or scrolling and operation is then followed in order to display the image data of the next page, thus resetting display control data on the display position and state set by the previous display operation for the image data of the previous page and initializing the display position and state of the image data of the next page. For this reason, in order to display the image data of the next page at the same display position and state as those of the previous page, it is necessary to repeat the operation for enlargement, reduction, rotation or scrolling. Whenever, accordingly, image data different from those of the next coming page are tried to be displayed by the pressing of the "next page" key, the repetition of the operation is required in order to change the display position and state on the display screen of the display section to an objective display position and state from the initialized state on the display screen thereof. This operation is extremely laborious.